MMU Under Shelf Auto Rewind Spool Holders

*** Update *** Added new v3 Spool and Spring see here for details https://www.thingiverse.com/thing:3248031

I also added the Black bumper / spacers called "Spool Holder Bracket Spacer Guide.stl" these can be clipped on the the side brackets and stop spools getting too close to the edge.

Inspired by Vincent Groenhuis Auto Rewind Spool https://www.thingiverse.com/thing:3200204 I decided I needed to make under the shelf / Hanging Spool Holders for these.

This uses the metal rods and 608 bearings from the Prusa MMU spool holders.

I added a square end stop to the spring design from Vincent Groenhuis and then made some Hangers for them.

The Hangers print flat so easy to print and I printed mine in PLA. You need 1x Base and 2x Side Brackets for each set. The side brackets press firmly in to the base and you can then screw them up as one piece. Liking to make things easy for myself I made the base units slot together with tabs, so once you have your first holder in place the others just push up and slot in to the existing one and you can then screw that in to place as well. Less measuring :)

For the Auto Rewind spool you will need

1x Wide Hub https://www.thingiverse.com/download:5570849 from Vincent Groenhuis original design.
1x Spring Remake https://www.thingiverse.com/thing:3248031 from my Remake of the Spring which includes the square end stop.

Print the Spring at least in PETG I found PLA lost a bit of its springiness over time (PETG still going well). I also printed the Wide Hub in PETG so they were the same once glued together.

To assemble the Spool push one metal rod in to the square end stop through the spring, these are a tight fit so make sure you push it to the end.

Push a 608 bearing in to each side of the Wide Hub.

Then glue the Spring to the Wide Hub. Make sure you only glue around the edge of the Hub as the rest of the spring needs to be able to move. As the spring is already on the metal rod you can slide this rod through both bearings in the Hub and this will help you glue the spring on centred.

Once together you can push on the round Spool End Cap to the other side to keep it all together, again this is a snug fit so push it on all the way. To be sure you have this pushed all the way on the final length of the whole shaft including end stops should be 22mm - 23mm long.

I have included pictures so this should help.

I also made a through the shelf PTFE tube holder / feeder which takes the M10 PTFE tube connectors. see M10 Feeder Mount in the files section. You will need to purchase an M10 connector for each one.

Most of my Filament Spools work fine with this setup and stay centred on the spool, but I did find the odd spool would wonder slowly to the side of the spool. So I also made a clip on guide "Spool Holder Bracket Spacer Guide" in the files section. This pushes on to the Side Brackets (See photos its the black part on the side brackets) and it stops a Spool reel from wondering to far to the edge.

I found the Prusa Spool holders to be very fiddly to use, feeding the filament through holes and elbows etc. then only having a few inchs to be able to feed the filament all the way to the MMU. With my new setup changing spools is very quick with load of space to feed / push filament down the tubes.

I hope you find this useful and please post a make to Thingiverse if you do make one.

FYI The Green Spool Holder in the pictures was PLA and you can see the spring lost a little springiness. The Black ones are PETG :)

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